An ID saw slicing machine is a slicing machine equipped with a thin doughnut-shaped blade with the inner edge coated with a hard material such as diamond powder. This machine is particularly useful in slicing a brittle rod such as a single crystal semiconductor ingot. As the blade of the ID saw slicing machine is rotated at a predetermined high speed, either the ingot or the slicing machine is slided in a manner such that the blade crosses the ingot in a direction normal to the axis of the ingot. The rate of this crossing of the blade is called "feed" or "feed rate" and measured in terms of a distance per unit time, e.g. "mm/min."
In the technical field of semiconductor manufacturing, a silicon single crystal ingot pulled up in a conventional single crystal pulling apparatus is sliced with an ID saw slicing machine (hereinafter also referred to as "an ID slicer") in a direction normal to the axis of the ingot, and a number of silicon semiconductor wafers are cut out. After a long use, the blade of the ID slicer wears and starts wobbling, and this causes the sliced wafer to show so-called face bow, which is a warp in one direction, or in other words, the residual stress in the wafer causes the wafers to curl slightly.
In order to solve this problem, some of the commercially available ID slicers are equipped with a displacement gauge which measures the wobble displacement of the blade of the slicer. The wobbling of the blade is detected by means of the displacement gauge, and based on the result of the detection, the blade is appropriately dressed and trued; also the slicing rate is modified in response to the result of the detection of the blade displacement in a feedback manner. Thus, efforts have been made in an attempt to obtain semiconductor wafers having as small a bow as possible.